ISOLATION AND PURIFICATION OF SELENIUM-LEACHING BACTERIA FROM COPPER REFINERY ANODE SLIME

Background and Aim:Anode slime from copper electro-refining normally contains various metals such as selenium, tellurium, copper, silver, nickel, platinum group metals (PGM), barium, iron, gold, lead that has a high commercial value. Generally anode slimes are processed to recover silver, gold, selenium and tellurium. Bioleaching is an effective technology for metal recovery that is performed by microorganisms. Selenium is a strategic element which is essential for all organisms and has a wide range application in industry.Methods:The current work attempts to isolate strains from copper refinery anode slime which are capable of selenium bioleaching. In order to achieve this aim, Tryptic Soy Broth and Luria-Bertani media with anode slime incubated at 30˚C for three weeks. During this time, samples from these media cultured on Tryptic Soy Agar and Nutrient Agar. Then bioleaching tests carried out by the isolated and purified bacteria and leach liquor analyzed by Inductively Coupled Plasma-Optical Emission Spectroscopy (Perkin Elmer Optima 7300DV).Results:In this research, four Gram-positive and one Gram-negative rod-shaped bacteria were isolated. On average, these bacteria had the ability to solubilize 6.66 mg/l selenium from copper anode slime.Conclusion:Copper anode slime contains toxic forms of elements, so leaching-bacteria should be able to grow in this rough condition. Screening from anode slime has the advantage of isolating resistant bacteria to harsh condition of this slime. Thus, each of the isolated bacteria can be a suitable candidate for selenium bioleaching processes from secondary resources due to the unique resistance of these bacteria.

کلیدواژه ها:

Copper anode slime ، Bioleaching ، Selenium ، Metal extraction